Bill Ackman’s Pershing Square has climbed into the top ranks of hedge funds in January with a 4 percent gain, according to investor reports.

Pershing Square’s $12 billion firm outdid the S&P 500, which had a glum month, as did some of his peers.

The S&P 500 fell 3.5 percent while Dan Loeb’s Third Point and David Einhorn’s Greenlight Capital each fell 1.5 percent.

By Jan. 15, Ackman’s fund had jumped into the widely watched Top 20 ranking of hedge funds, as ranked by HSBC.

Pershing Square’s gains were fueled by an 18.2 percent drop in Herbalife shares, following news that Sen. Ed Markey (D-Mass.) has called for Federal Trade Commission and Securities Exchange Commission investigations into the company.

Meanwhile, Ackman’s Herbalife short has grown 16 percent, to $1.16 billion, according to the investor report.

Pershing also profited on the merger agreement between Japan’s Suntory and Beam, which rose 22.4 percent for the month. Last week, Pershing Square cut its stake in Beam.